Fabrication of graphene/Titania nanograss composite on shape memory alloy as photoanodes for photoelectrochemical studies: Role of the graphene

Abstract

In this study, hierarchical composites of Titania-graphene nanograss arrays (TiO2@Gr) on shape memory alloy were prepared via chemical vapor deposition-controlled growth process (camphor as source) and subsequent hydrothermal method. The TiO2@Gr composite composition was optimized by varying the concentrations of graphene on TiO2 nanograss grown over shape memory alloy. The optical, surface, and structural studies of as-prepared TiO2@Gr composite were performed under UV–vis spectroscopy, Field Emission Scanning Electron Microscope, Transmission Electron Microscope, Raman, X-ray diffraction and X-ray photoelectron spectroscopy. The result revealed the formation of pure rutile phase Titania nanograss with the impregnation of graphene sheets. Further, the impregnated graphene-Titania composite samples were used as photoanodes (photoelectrode) in 1 M potassium hydroxide solution for photoelectrochemical application. The results revealed an enhancement in photocurrent density of 1.82 mA/cm2 at 1.23 V vs. reversible hydrogen electrode, signifying excellent photoelectrochemical performance superior to that of pure rutile titania (nearly 3.5 times), which is attributed to a synergetic effect of the improved electron-hole pair separation rate leading to superior charge transfer due to the presence of graphene nanosheets. Transient photo-response studies (TPS) and Electrochemical impedance spectroscopy (EIS) were used to study the effective charge transfer response and interfacial charge transfer process respectively. The approach for the fabrication of the hierarchical nanocomposite in this study may drive the way for designing innovative composite materials for enhanced photoelectrochemical performance.